CMake为Xcode目标与正常目标

Posted 2021-03-27

我有这个简单的C ++ 11代码。

#include <vector>
#include <iostream>
#include <memory>

using namespace std;

class A
{
    int x;
public:
    A() {}
    ~A() {}
    A(A& a) {}
    A(int x) {this->x = x;}
    int get() {return x;}
};

int main()
{
    vector<unique_ptr<A>> v;
    auto a = new A(10);
    unique_ptr<A> pa(a);
    v.push_back(move(pa)); // move(pa);

    auto a2 = new A(20);
    unique_ptr<A> pb(a2);
    v.push_back(move(pb)); // move(pa);

    for (auto& i: v)
    {
        cout << i->get();
    }
}

我正在尝试使用Xcode和clang ++上的CMake设置来构建此代码。

这是CMakeLists.txt文件：

cmake_minimum_required(VERSION 2.8)
project( testit )

set(CMAKE_CXX_FLAGS "-std=c++11 -stdlib=libc++")

set(testit
    testit.cpp
    )

add_executable(gv ${testit})

clang ++ build。

1. mkdir build和cd build
2. export CC=/usr/bin/clang
3. export CXX=/usr/bin/clang++
4. cmake ..
5. make

我可以得到工作正常的二进制文件。

Xcode 4.5 target

1. 同样的步骤1-3
2. cmake .. -G Xcode
3. xcodebuild

编译工作正常，但我在构建中出现Undefined symbol错误。我在CMake set(CMAKE_CXX_FLAGS "-std=c++11 -stdlib=libc++")中使用此命令设置C ++ 11。

Undefined symbols for architecture x86_64:
  "std::__1::__vector_base_common<true>::__throw_length_error() const", referenced from:
      void std::__1::vector<std::__1::unique_ptr<A, std::__1::default_delete<A> >, std::__1::allocator<std::__1::unique_ptr<A, std::__1::default_delete<A> > > >::__push_back_slow_path<std::__1::unique_ptr<A, std::__1::default_delete<A> > >(std::__1::unique_ptr<A, std::__1::default_delete<A> >&&) in testit.o
  "std::__1::basic_ostream<char, std::__1::char_traits<char> >::operator<<(int)", referenced from:
      _main in testit.o
  "std::__1::cout", referenced from:
      _main in testit.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

可能有什么问题？

ADDED

从这个链接看来，目标设置错误来自CMake的xbuildcode：http://www.executionunit.com/blog/2012/10/27/xcode-std-link-errors/

ADDED

我可以解决这个问题，但我必须使用CMakeLists.txt文件所在的同一目录。

当我执行CMake .. -G XCode时，我收到了另一个错误。

=== BUILD AGGREGATE TARGET ZERO_CHECK OF PROJECT XcodeTest WITH THE DEFAULT CONFIGURATION (Debug) ===
Check dependencies

PhaseScriptExecution "CMake Rules" build/XcodeTest.build/Debug/ZERO_CHECK.build/Script-BED7FB205C634C34A1ACD293.sh
    cd /Users/smcho/Desktop/cmake
    /bin/sh -c /Users/smcho/Desktop/cmake/build/XcodeTest.build/Debug/ZERO_CHECK.build/Script-BED7FB205C634C34A1ACD293.sh
echo ""

make -f /Users/smcho/Desktop/cmake/build/CMakeScripts/ReRunCMake.make
make[1]: *** No rule to make target `/Users/smcho/Desktop/cmake/build/CMakeFiles/2.8.10.2/CMakeCCompiler.cmake', needed by `CMakeFiles/cmake.check_cache'.  Stop.
make: *** [/Users/smcho/Desktop/cmake/build/CMakeFiles/ZERO_CHECK] Error 2
Command /bin/sh failed with exit code 2

** BUILD FAILED **

The following build commands failed:
    PhaseScriptExecution "CMake Rules" build/XcodeTest.build/Debug/ZERO_CHECK.build/Script-BED7FB205C634C34A1ACD293.sh

答案

有两个问题。

链接选项

正如Fraser指出的那样，问题来自链接器中的设置。

...    
set(CMAKE_CXX_FLAGS "-std=c++11 -stdlib=libc++")
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -stdlib=libc++")
...

Add_subdirectory

我不知道为什么会这样，但我需要在主CMakeLists.txt文件中使用add_subdirectory(src)，并在该src目录中创建另一个CMakeLists.txt文件，以便在build目录中运行CMake。没有它，我必须在CMakeLists.txt文件所在的同一目录中运行CMake。请参阅Stack Overflow问题CMake Xcode generator creates a project that cannot build

这是src目录中的CMakeLists.txt：

set(CMAKE_CXX_FLAGS "-std=c++11 -stdlib=libc++")
file ( GLOB SRCS *.cpp )
add_executable( program ${SRCS})

这是主目录中的CMakeLists.txt：

project( XcodeTest )
cmake_minimum_required( VERSION 2.6 )

set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -stdlib=libc++")

add_subdirectory(src)

我从这个YouTube视频中得到了提示：CMake XCode Demo